1. Field of the Invention
The present invention relates to image processor for combining a coded image into a print image.
2. Description of the Related Art
In recent years, a technique of combining a coded image obtained by coding data into an image (subject image) to be displayed or printed, then extracting the coded image on the decoding side, then decoding the data from the coded image and utilizing the data, has been developed.
According to this technique, the coded image, in a so-called semi-transparent state, is combined into the image to be printed, while the visibility of the subject image is maintained. More particularly, as shown in FIG. 8, coded image elements corresponding to “0” and “1” bits are arrayed in accordance with the data to be coded, and the brightness of pixels of the subject image is reduced by a value obtained by multiplying the pixel brightness of the coded image by a predetermined value. Among the pixels of the coded image elements in FIG. 8, the brightness of “white” pixel is “0”, and the brightness of “black” pixel is “255”.
Generally, as in the above-described coded image combining, a coded image is combined in an area which satisfies predetermined conditions in a subject image. However, detection of such an area causes a heavy load, and further, the subject image does not always include an appropriate area satisfying the conditions. Accordingly, in the conventional coded image combining techniques, the processing is comparatively complicated.
For example, as in the case of PDF (Portable Document Format), in a case where annotation information is linked to a document as if the information were a so-called “tag”, and the annotation information can be printed with the document, the annotation information is usually an image comparatively appropriate for coded image combining (e.g., a character string is described on a colored background). Accordingly, a coded image may be combined with the image of the annotation information.
However, since there are various sizes of annotation information images whereas the size of data to be included in the coded image is not constant, the entire coded image cannot always be combined in the annotation information image.